1. Field of the Invention
The present invention relates, in general, to a suction resonator system installed in an air suction part of an internal combustion engine and used for reducing suction noises of the suction system by offsetting the suction frequency of the suction system using a tuning frequency and, more particularly, to a variable suction resonator system capable of generating a variable tuning frequency suitable for effectively reducing the suction noises regardless of suction frequencies variable in accordance with the rpm of an engine.
2. Description of the Prior Art
FIG. 3 shows the construction of a typical suction resonator system for internal combustion engines. As shown in the drawing, the typical suction resonator system comprises a suction duct 10 through which atmospheric air is sucked into a cylinder (not shown) of an engine. A resonator 12 is connected to the suction duct 10 through a neck 11 and generates a resonance frequency.
In the operation of the above resonator system, the resonator 12 forms a wave motion, which has a tuning frequency corresponding to the frequency of air flowing through the duct 10, thus reducing suction noises generated from the sucked air in the duct 10.
As well known to those skilled in the art, such suction noises are variable in accordance with the rpm of an engine. Therefore, when such a resonator 12 is designed, it is necessary to perform an analysis of variable suction frequencies within a range of expected rpm of an engine prior to determining a suction frequency, which generates the loudest suction noise, thus being most effectively offset by the tuning frequency of the resonator 12.
In such a resonator 12, the tuning frequency (f) is determined by the volume (V') of the resonator 12 and the sectional area (S) and length (l') of the neck 11 as will be represented by the following expression. EQU f=C/2.pi.!.multidot.{.sqroot.S/(l'+.delta.).multidot.V'!}
wherein C is a constant, and .delta. is a compensation parameter for the variable configuration of the neck 11.
However, such a suction resonator system is problematic in that it is designed to generate a fixed tuning frequency, which does not effectively meet and offset the suction frequencies variable in accordance with the rpm of an engine, thus failing to effectively reduce suction noises of the engine.